Question: Khan.scratchpad.disable(); To move up to the maestro level in his piano school, Luis needs to master at least $91$ songs. Luis has already mastered $19$ songs. If Luis can master $7$ songs per month, what is the minimum number of months it will take him to move to the maestro level?
Answer: To solve this, let's set up an expression to show how many songs Luis will have mastered after each month. Number of songs mastered $=$ $ $ Months at school $\times$ Songs mastered per month $+$ Songs already mastered Since Luis Needs to have at least $91$ songs mastered to move to maestro level, we can set up an inequality to find the number of months needed. Number of songs mastered $\geq 91$ Months at school $\times$ Songs mastered per month $ +$ Songs already mastered $\geq 91$ We are solving for the months spent at school, so let the number of months be represented by the variable $x$ We can now plug in: $x \cdot 7 + 19 \geq 91$ $ x \cdot 7 \geq 91 - 19 $ $ x \cdot 7 \geq 72 $ $x \geq \dfrac{72}{7} \approx 10.29$ Since we only care about whole months that Luis has spent working, we round $10.29$ up to $11$ Luis must work for at least 11 months.